var obj = new Object("hello");
var obj2 = new Object(5);
console.log(obj instanceof Object);
console.log(obj instanceof String);
console.log(obj2 instanceof Object);
console.log(obj2 instanceof Number);

var oBoolean = new Boolean();
console.log(oBoolean);
console.log(Boolean(oBoolean));
if(Boolean){
    console.log("这个对象存在");
    
}

console.log(Number.MAX_VALUE);
console.log(Number.POSITIVE_INFINITY);
console.log(Number.NEGATIVE_INFINITY);

var numbers = new Number(256);
console.log(numbers.toString(16));
var result =  parseInt("22");
console.log(result);
// console.log(isIn("23"));

var n = new Number(3.14159);
console.log(n.toFixed(2));
//数学样式
console.log(n.toExponential(2));

var str = new String("你好啊");
console.log(str.length);
console.log(str.charAt(1));
console.log(str[1]);

var str2 = new String("世界");
var rr = str.concat(str2);
console.log(rr);


var charStr = "ABCDEFG";
console.log(charStr.slice(1,3));
console.log(charStr.substr(1,3));
console.log(charStr.substring(1,3));
console.log(charStr.substring(1));








